Drill Stops are accessories which fasten to twist or brad point drills to prevent excessive drill penetration. Positive depth control assures exact hole depths when performing tasks such as pre-drilling screw holes, or roughing out mortises. Black oxide finish on cold rolled steel. An accurate bore size and hex tightening screw allow easy, secure fastening onto the bit. Six piece set includes sizes from 3/16" to 1/2" and a hex wrench.